spongebob is holding the sub, similar to how the water held up the german underbotten that sunk the lusitania. this is obviously an allusion to the beginning of WW2
You're close. The sub sandwich represents a state of mind in which a man can have perfect sanity, yet in an instant snap and commit horrible crimes.
In spongebob lore, it's not until the post-krabby patty era that spongebob's psychotic tendencies were diagnosed. The reason spongebob confused a bank teller with a doctor is because like his pediatrician, spongebob doesn't trust anyone and feels they're all just like his doctor. After spongebob committed murder, he spent the remaining hours of his life breaking into houses and going trick-or-treating, trying to keep in touch with a part of his life (his childhood) where he remained innocent
In the end, spongebob is turned into plasma and the red guy eats cheese whiz
